The typical modern wind turbine includes a tower that supports a nacelle at an upper end thereof. A rotor having a central hub and one or more blades is coupled to the nacelle and converts the kinetic energy of the wind into mechanical energy, usually in the form of a rotating main shaft. The nacelle includes various components that convert the mechanical energy from the rotor into electrical energy. For example, the nacelle generally includes a drive train and an electrical generator that collectively facilitate the production of electrical energy. More particularly, the drive train transforms the mechanical energy of the rotor into a suitable input for the electrical generator. In this regard, the drive train may include a gearbox that transforms the generally low angular velocity main shaft into a higher angular velocity secondary shaft. The secondary shaft is, in turn, operatively coupled to the electrical generator for rotating the generator rotor relative to the stator so as to produce electrical energy. The nacelle also includes various components that provide for the efficient operation of the wind turbine (e.g., pitch mechanism, yaw mechanism, brake mechanism, etc.). As such, the nacelle operates as a housing for many of the primary internal components that result in the efficient operation of the wind turbine.
During initial installation or during repair or replacement operations, there may be a need to access the interior of the nacelle. By way of example, there may be a need for personnel, such as engineers, repairmen, technicians, or the like, to gain access to the interior of the nacelle. Moreover, there may be a need to transport various pieces of equipment to the interior of the nacelle. This may include, for example, original components, replacement components, spare parts, tools, and the like. There may also be a need to transport personnel and various pieces of equipment out of the interior of the nacelle at the end of an install or repair operation. Conventionally, the transportation of personnel and equipment to or from the interior of the nacelle is achieved through the tower. More particularly, the tower may include an internal lift system (e.g., elevator or the like) that transports personnel and/or equipment from the bottom of the tower, which may be conveniently accessed through a door or hatch adjacent the base of the tower, to the upper end of the tower, and vice versa. The tower is typically open at its upper end face and this opening has traditionally provided the access point to the interior of the nacelle.
However, accessing the nacelle through the opening in the upper end face of the tower has certain limitations and drawbacks. By way of example, as the size of wind turbines increases, the size of the drive train, generator, and associated components within the nacelle also increases, thereby limiting the available space for the access opening within the nacelle. Moreover, it is often desirable to locate the drive train adjacent the front wall of the nacelle through which the main shaft extends (i.e., the wall that confronts the wind turbine rotor). Such a location, however, places the drive train adjacent the opening in the upper end face of the tower. Thus, the drive train and associate components are rapidly encroaching upon the opening in the tower, making access therethrough more difficult and problematic. For example, it is becoming more difficult to transport larger components, spare parts, etc. through the opening in the upper end face of the tower due to the crowded conditions in the nacelle adjacent the opening.
In addition to the above, on rare occasions, there may be a need to evacuate injured personnel from the nacelle. However, evacuating injured personnel from the nacelle through the opening in the upper end face of the tower can in some cases be problematic. In this regard, due to the location and size restriction, it may be difficult to transport stretchers and other emergency equipment through the opening in the upper end face of the tower. For example, a stretcher may have to be rotated toward its vertical orientation in order to pass through the opening in the upper end face of the tower. However, when an injured person is loaded onto the stretcher, it may be undesirable to position the stretcher in a vertical orientation or toward a vertical orientation in order to allow the stretcher to pass through the opening. Thus, the evacuation of injured personnel from the nacelle and through the tower can present certain challenges in current wind turbine designs.
Accordingly, Applicant has appreciated that there may be a need for an apparatus and associated methods that provide for improved access to the nacelle of the wind turbine via the tower in a manner that overcomes the drawbacks and problems associated with the conventional access route. More particularly, Applicant has appreciated that there may be a need for an apparatus and associated methods that provide access to the interior of the nacelle from the tower along a route that does not extend through the opening in the upper end face of the tower.